Q. Why can’t I adjust the "X" Back harnesses to fit my dog? A. The simple reasons are : Placing adjustment mechanisms, i.e., clips and fastenings within the harness, can cause abrasions to the dog. Invariably, adjusters can break and stretch, which means you are always putting the harness back to it’s original position before usage, and in the majority of cases, it just adds more weight to the harness. Some mushers are acutely aware of weight burden issues.